Understanding Axle Wrap
Axle wrap occurs when the rotational force of the tires causes the axle housing to twist or rotate: a reaction to torque either from the engine on acceleration or braking force on deceleration. (Most noticeable on hill climbs while accelerating or when hard braking). This rotation of the axlehousing forces the springs to bend into an s-shape. When the axlehousing rotates far enough the resulting spring force tries to push the housing in the opposite direction while the u-joint attempts to make a straight line between the axle assembly yoke and driveshaft. These forces cause the tires to loose traction and jump or "hop". Once traction is lost, the springs snap back into their original positions.
This twist and release happens over and over until the vehicle either gains better traction or the driver reduces torque input by letting off the throttle or brake. As the axlehousing rotates under load, the pinion angle changes. This means the yoke on the axlehousing moves up or down in relation to the driveshaft. During acceleration, axle wrap can cause driveline vibrations because of the increased u-joint angle at the pinion yoke. In extreme cases, this increased angle exceeds the limits of the u-joint and causes it to fail or rapidly wear out.
Wheel Hop (the rapid up/down motion of the tires as a result of axle wrap) places loads on the internal components of an axle assembly. Putting these components under excessive strain can lead to failure. The leaf springs are also affected because the extra stress caused by bending under load wears them out more quickly. Finally, traction is reduced because the tires do not transfer torque to the ground as efficiently.
The "Heavy Load" columns in the Application Guide show the Optional heavy duty XX Roadmaster kit that should be fitted to vehicles towing or hauling heavy loads. This XX option is highly recommended, when applicable, for vehicles that carry a full load of passengers, 5th wheel trailers, slide-in campers, construction and landscaping equipment or materials (in bed or towed), ATV's or Snowmobiles, automobiles or large boat trailers, etc., etc.
In order to set the Roadmaster coil springs to the correct tension, the leaf springs must be in their maximum arched position. Therefore, to achieve correct tension the rear axle Must be hanging free with NO Load on the leaf springs. Lift vehicle only via the frame.
Exceeding Tension Setting:
Never exceed the recommended coil spring tension setting, as stated in the Roadmaster kit installation instructions.
Watch For Obstrucions:
When installing the Roadmaster System, make sure that the unit Does Not interfer with any brake lines, brake cables, air conditioning or heater hoses or any other obstructions. When installation is complete and the vehicle is set down, inspect the undercarriage again to ensure the operation of the system will be obstruction free.
When installing the Roadmaster system on a heavy duty pickup truck, that has an overload spring located above each pack of leaf springs, the overload spring MUST FIRST BE REMOVED. It is also recommended that the rear snubber located on the truck frame be removed as this could cause damage to Roadmaster components.
Follow fitting instructions to ensure proper fastener locking procedure as this is important for the ongoing performance of the Roadmaster System. After installation, check all fasteners to insure that proper locking has occured.
RAS and/or U-Bolt Removal
Caution: Always reduce coil spring tension to zero prior to attempting system or u-bolt removal. This is achieved by: 1) unscrewing the two nuts that lock the threaded rod to the coil spring. 2) hold the jam nuts located on the end of the threaded rod with a wrench. 3) turn the cap screw (which is locked to the coil spring) anti-clockwise until the tension on the spring is zero.
RAS Will Increase Load Carrying Capacity 50% Above O.E.M. Rating